Bigleaf hydrangea (Hydrangea macrophylla) is a deciduous shrub with large mophead or flat lacecap flowers from June into autumn. It needs partial shade – morning sun is ideal – and humus-rich, moisture-retentive soil; midday sun and dry soil make the leaves wilt within hours. On many varieties the flower colour depends on the soil: acid soil (pH 5.0–5.5) with available aluminium gives blue flowers, neutral to alkaline soil pink ones. Water deeply and often in summer, preferably with rainwater, and mulch with bark or leaf mould. Pruning needs care, because most varieties form next year's flower buds in the previous autumn: in March, cut out only dead and weak shoots and remove last year's flower heads down to the first pair of strong buds. Leave faded flowers on over winter to protect those buds. Late spring frosts can still damage emerging shoots, so cover young plants with fleece on cold nights. Remontant varieties such as the 'Endless Summer' series also flower on new shoots.